Silica gel is an important material, widely used in industry and daily life to absorb moisture and humidity. Its unique chemical and physical properties make it a rational desiccant choice.
I. Structure and properties of silica gel desiccant
Silica gel bead is a porous substance mainly composed of silicic acid gel, with a chemical formula of SiO2.nH2O. The structural characteristics of silica gel desiccant is that it contains a large number of micropores inside, which form a huge specific surface area, which is the basis of its moisture absorption ability. The pore size of granular silica gel can range from a few nanometers to hundreds of nanometers, which enables it to adsorb molecules of various sizes, including water molecules. Another important property of silica gel is its chemical inertness, which means that it does not react with most chemicals and is stable even at high temperatures. In addition, gel silica has the characteristics of non-toxicity, odorlessness, and non-corrosiveness.
II. Moisture absorption principle
The moisture absorption principle of silica gel desiccant is mainly based on two processes: physical adsorption and chemical adsorption
1. Physical adsorption
Physical adsorption refers to the non-covalent bonding between silica gel pores and water molecules due to intermolecular forces. When water molecules in the air come into contact with the surface of it, these molecules are attracted by the electrostatic force in the pores and enter the interior of the pores. Since silica gel has a very large specific surface area, it can effectively adsorb a large number of water molecules.
2. Chemical adsorption
Chemical adsorption refers to the chemical reaction between silica gel and water molecules. Although silica gel itself does not react chemically with water molecules, under certain conditions, such as high temperature or the presence of other chemicals,it may react with certain hydrolysis products to achieve chemical adsorption of moisture.
III. Classification of silica gel desiccant
Silica gel desiccant can be divided into white gel silica, blue blue silica, orange gel silica and alumina gel silica. White silica gel and alumina silica gel are non-indicative, while blue silica gel and orange silica gel are indicating silica gel. During the water absorption process, the blue one will turn pink, while the orange one will turn green.
IV. Application of silica gel desiccant
Silica gel particle is widely used in various fields due to its unique hygroscopic properties and safety. Such as natural gas dehydration, oil and gas recovery hydrophobicity, electronic products, pharmaceutical packaging, equipment and instruments, air compression systems, etc.
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